1. Field of the Invention
This invention generally relates to an injector having utility in angiography and/or angioplasty applications, and capable of delivering fluid at multiple selected pressures.
2. Description of The Related Art
In the field of angiography, a contrast medium such as iodine or other fluid of suitable indicating character (radiopacity) is introduced under pressure into coronary arteries, and the arterial network then is monitored by fluoroscopic or other visualizing means. As a result, arterial plaque deposits and/or other arterial occlusions are readily visually determined as to their size and location, so that suitable treatment methods, such as removal of the occluding material by lasing or mechanical excision, or displacement techniques such as balloon angioplasty, may be carried out.
To effect the introduction of the contrast medium into the arterial network for angiographic study, it has been common practice to utilize injector syringes in combination with arterial catheters. The syringe may be hand-held, or machine mounted, and is connected at its distal end to the catheter which is introduced into the arterial system to be studied.
In the angiography procedure, the arterial catheter attached to the injector syringe is typically introduced into the femoral artery and subsequently translated in the arterial passage toward the heart. During this "threading" procedure through the arterial network, it frequently is desirable to inject small volumes of the contrast medium from the syringe into the catheter for discharge at the distal end of the catheter, in order that radiographic detection of the catheter distal end may be achieved, and the arterial catheter may be properly directed to the desired arterial locus.
Thus, small volumes of the contrast medium are injected for guidance, and it is desired to minimize the actual volume discharged at the distal end of the catheter, in order to precisely locate the catheter's distal end, as well as to avoid undue introduction of excessive amounts of the contrast media into the vascular network, such as may be deleterious to the subject being catheterized. Accordingly, close control of the injection of such "guidance volumes" is required.
Further, when small volume blood vessels are present in the arterial network to be studied, either of intrinsically small size, or of reduced diameter due to conditions such as atherosclerosis, relatively smaller volumes of the contrast medium are employed, and higher pressure injection is necessary.
Thus, in the broad practice of angiography utilizing injector syringes and associated arterial catheters, situations are encountered requiring widely divergent pressure levels and volumes of introduced medium. Unfortunately, the injector syringes heretofore employed in angiographic applications do not possess any capability for varying the pressure level of the introduced contrast medium.
Apart from the foregoing, syringes have also been employed as fluid delivery devices in balloon angioplasty applications, in which a ballon catheter having a deflated balloon at its distal end is introduced into an artery for translation therein to the site of arterial blockage, e.g., plaque deposit, and a syringe device at the proximal end of the balloon catheter is employed to introduce fluid into the balloon to expand same, thereby displacing the arterial occlusion and enlarging the cross-sectional flow area in the artery at the previously occluded site. After the balloon has been inflated to a predetermined or selected extent, typically involving pressures of up to about 300 psi, or to even higher pressures, the pressure on the balloon is released, typically by a "quick-release" lever mounted on, or associated with, the inflation syringe ("endoflator").
In balloon angioplasty applications, precise control of the inflation pressure level is critical to achieving the desired de-occlusion of the arterial passage being treated. Further, there is a degree of "art" involved in the angioplasty procedure, in that the thoracic surgeon or other individual doing the balloon angioplasty procedure typically adjusts the balloon pressure to a predetermined set value in the vicinity of that anticipated to be required to adequately inflate the balloon, followed by some additional "fine tuning" adjustment to get the proper "feel" of fluid pressure resistance on the plunger of the inflation syringe, indicative of an effective level of inflation being achieved in the balloon.
Presently, there is an extensive and increasing use of hand-held syringes of various sizes, as well as machine-assisted syringes, in the medical technology field, for injecting fluids into catheter balloons, blood vessls, and other physiological loci. Such injection is typically done under elevated pressure conditions, and must be carried out in a highly accurate manner in terms of introduced fluid volumes and pressure levels. Consistent with a trend toward higher injection pressures, and to better enable the syringe operator to exert effective pressures on hand-held syringes, the medical products industry has evolved syringes having sturdier finger and thumb grips, so that higher pressure levels can be manually applied, relative to hand-held syringes previously in use.
Thus, there is a continuing need in the art to provide syringes having a flexible character for providing moderate presssure injection levels, as for example on the order of up to about 100 psi, as well as higher injection pressures, e.g., up to about 1,000 psi and above, in the case of power injector systems.
U.S. Pat. No. 984,037 to J. H. Sheets discloses a syringe comprising a ported hollow piston rod, having a port at the distal end of the rod as well as a proximal port open to the exterior environment. Such arrangement allows liquid to flow through an open passage in the piston, and to flow proximally of the piston, or distally thereof, as desired. See also the vial syringe disclosed in J. H. Sheets' U.S. Pat. No. 1,707,880, representing an improvement over his earlier patented syringe.
U.S. Pat. No. 1,950,137 to F. Le C. Dowe describes a double-barreled, double-plunger syringe, in which the distal end of the syringe is formed with separate passages communicating with the respective inner and outer barrels, depending on the relative position therebetween. A piston is provided in the outer barrel, attached to finger grips which are vertically adjustable in a corresponding track. The finger grips are attached to a spring, and the track has a saw tooth surface for ratchet action retention of the piston in a desired position. By this construction, the inner barrel is said to be selectively rotatable so that blood may be withdrawn from varicose veins and treatment solution injected without removing the syringe or changing its position, and without the withdrawn blood and the treatment solution coming in contact with one another.
U.S. Pat. No. 1,234,582 to B. T. Trueblood discloses a sequential injection hypodermic syringe, in which a first material in an outer barrel of the syringe is injected by forwardly advancing the inner barrel, and then a second substance contained in the inner barrel is injected by forwardly advancing a plunger resposed in the inner barrel.
A tandem syringe is described in U.S. Pat. No. 2,939,459 to J. A. Lazarte, et al in which the inner barrel of a two-barrel syringe is provided on its anterior face with a puncturable resilient diaphragm, so that a syringe needle extending into the interior of the outer barrel is able to pierce the diaphragm. The inner barrel is fillable with a first volume of a solution, and the diaphragm is of a self-resealable character, so that when the inner barrel is proximally withdrawn from the distal end, a second volume of solution may be introduced into the outer barrel.
Other sequential filling/dispensing syringe constructions having multiple barrel or plunger structures include U.S. Pat. No. 3,749,084 to A. L. Cucchiara; U.S. Pat. No. 4,188,949 to W. T. Antoshkiw; U.S. Pat. No. 4,313,440 to S. J. Ashley; and U.S. Pat. No. 4,702,737 to J. L. Pizzino.
Single barrel compartmentalized syringes are also known, such as the mixing syringe of U.S. Pat. No. 4,116,240 to A. C. Guiney, and various single barrel syringes have been developed containing free floating barriers for forming separate chambers in the barrel, such as U.S. Pat. No. 3,985,122 to S. C. Topham; U.S. Pat. No. 4,044,758 to B. C. Patel; and U.S. Pat. No. 4,439,184 to R. P. Wheeler.
Other multiple-chambered injection apparatus are disclosed in U.S. Pat. No. 4,214,584 to B. A. Smirnov, et al and U.S. Pat. No. 4,655,747 to R. E. Allen, Jr.
With respect to the distal coupling means of the syringe of the present invention, leur connector devices are disclosed in U.S. Pat. No. 4,452,473 to R. R. Ruschke, and U.S. Pat. No. 4,629,455 to M. Kanno. A two-piece swivel coupling for a catheter system having luer connections on either end of the coupling is disclosed in U.S. Pat. No. 4,254,773 to C. C. Waldbillig.
U.S. Pat. No. 4,758,223 to M. A. Rydell discloses a hand-operated inflator for balloon-type catheters, including first and second coaxially disposed plunger operated pistons within a tubular syringe housing comprising a first, relatively large diameter tubular syringe portion and an integrally joined second tubular syringe portion of lesser diameter. The angioplasty catheter is filled by forcing the contents of the larger diameter syringe portion through the catheter by depressing the first plunger coupled to the large diameter piston. After the catheter has been filled in such manner, the pressure in the dilation expander member is adjusted by manipulating the piston cooperating with the smaller diameter syringe portion. The patent states that by incorporating the two syringes in the same housing, a large volume of fluid such as a radiopaque contrast medium can be injected through the catheter and out its distal end, while the small diameter and volume syringe can be used to pressurize the expander with considerably less effort than if the large diameter syringe alone had been used.
The Rydell patent at column 6, lines 45-49 thereof, discloses an illustrative embodiment wherein the larger diameter syringe portion has a volume of approximately 10 cc. and the smaller diameter portion has a volume of approximately 2 cc. In the embodiment of the invention shown in FIG. 4 of this patent, the smaller diameter piston is attached to a knob by means of a pin which is longitudinally movable in a corresponding slot in the outer plunger. In this manner, the inflator operator can force the smaller piston into a correspondingly dimensioned distal passage in the outer barrel of the syringe.
In an alternative embodiment shown in FIGS. 6 and 7 of the Rydell patent, a freely rotatable sleeve is mounted on the outer piston and joined by means of a corresponding lateral pin to the inner piston. The pin joined to the inner piston is longitudinally translatable in a corresponding slot in the outer pistion. The sleeve in turn is helically grooved on its exterior surface to accommodate a pin joined to a finger grip structure. In this manner, the collar is rotatable to advance or retract the inner piston relative to the outer piston and the finger grip structure, so that a selected pressure can be maintained without manual gripping of the inflator.
It is an object of the present invention to provide an improved injector device having the capability of delivering fluid at different pressure levels.
It is another object of the present invention to provide an inflation device for balloon angioplasty, which has the capability of delivering pressurizing fluid at different pressure levels, and which features "quick-release" locking means for selectively holding and releasing selected pressures in the fluid delivered by the inflation device.
Other objects and advantages of the invention will be more fully apparent from the ensuing disclosure and appended claims.